refactor: Rename method to better convey its purpose

inc/Form/DropdownElement.php

@@ -165,7 +165,7 @@ class DropdownElement extends InputElement {
         $value_exists = false;
         /** @var OptGroup $optGroup */
         foreach (array_merge(array($this->options), $this->optGroups) as $optGroup) {
-            $value_exists = $optGroup->setValue($value) || $value_exists;
+            $value_exists = $optGroup->storeValue($value) || $value_exists;
             if ($value_exists) {
                 $value = null;
             }

inc/Form/OptGroup.php

@@ -18,14 +18,14 @@ class OptGroup extends Element {
     }
 
     /**
-     * Set the element's value
+     * Store the given value so it can be used during rendering
      *
      * This is intended to be only called from within @see DropdownElement::val()
      *
      * @param string $value
-     * @return bool
+     * @return bool true if an option with the given value exists, false otherwise
      */
-    public function setValue($value) {
+    public function storeValue($value) {
         $this->value = $value;
         return isset($this->options[$value]);
     }